Been gone for a while
Well, a 4x4 wil get you almost 4 more inches, a 6x6 will get you almost 6 more inches.....
Or, if you have a bumper jack, that works.
Or stack some 2x4's under the frame of the jack (a stack just behind the front wheels, and a stack just in front of the rear wheels). It is usually very stable as long as you don't go TOO high.